The present invention relates to a motor-vehicle door latch. More particularly this invention concerns such a latch which can be locked and unlocked.
A standard motor-vehicle door latch has a housing, a latch element displaceable in the housing between a position holding a bolt in the housing and a position freeing a bolt for movement into and out of the housing, and a pawl movable in the housing between a latched position retaining the latch element in the holding position and an unlatched position allowing the latch element to assume the freeing position. A release lever in the housing is engageable with the pawl and movable between an actuated position displacing the pawl into the unlatched position and an unactuated position leaving the pawl in the latched position. An actuating lever in the housing coupled to the door handle is pivotal on the housing on actuation of a door unlocking member. It is in turn operated at least by an outside handle and is coupled to the release lever so that the handle can operate the pawl through the actuating and release levers to unlatch the door.
There can be two actuating levers connected to respective inside and outside door handles and themselves connected together or operating a common actuating lever that in turn acts on the release lever. Furthermore the system is typically provided with a lock system that may be operated by a central-lock actuator, e.g. an electric motor, or by an inside lock button and/or an outside lock cylinder. In the standard system described in commonly owned U.S. Pat. No. 4,978,154 of Kleefeldt the lock system includes a member which can be shifted between a position coupling the actuating member(s) to the release lever and a position decoupling them. In the decoupled position actuation of the inside and/or outside door handle will be possible, but there will be no connection to the release lever so the actuation of the handle will not open the door. Such a system can also be provided with an antitheft position in which the inside lock button is also decoupled, making it impossible to unlock and unlatch the door from inside also.
A problem with this structure is that if the actuating lever is in its actuated position, the door cannot be unlocked. Thus merely holding out the outside door handle when the door is locked makes it impossible to unlock the door. Thus if the handle gets stuck in the out position, as for instance in an accident, the door will stay locked until it is moved back in. Otherwise operation of the latch functions while operating the lock members or vice versa can result in the mechanism locking up. This is particularly a problem with keyless entry systems where a person might be actuating a remote while another person is trying to op en a door. The door will not unlock until the person trying to open the door releases the handle and the person with the remote again actuates it to unlock the door.
It is therefore an object of the present invention to provide an improved motor-vehicle door latch.
Another object is the provision of such an improved motor-vehicle door latch which overcomes the above-given disadvantages, that is where actuation of the door handles does not interfere with the unlocking function.
A motor-vehicle door latch has according to the invention a housing, a latch element displaceable in the housing between a position holding a bolt in the housing and a position freeing a bolt for movement into and out of the housing, and a pawl movable in the housing between a latched position retaining the latch element in the holding position and an unlatched position allowing the latch element to assume the freeing position. A release lever in the housing engageable with the pawl is movable between an actuated position displacing the pawl into the unlatched position and an unactuated position leaving the pawl in the latched position. A lock member has an abutment in the housing engageable in a locked position with the release lever for inhibiting movement of the release lever from the unactuated position into the actuated position and unengageable in an unlocked position with the release lever for permitting movement of the release lever from the unactuated position into the actuated position. An actuating lever in the housing coupled to the door handle is pivotal on the housing on actuation of a door unlocking member, e.g. an inside or outside handle. An elastically compressible link in the housing is engaged between the actuating lever and the release lever for, in the unlocked position of the lock means, transmitting movement from the actuating lever to the release lever and thereby permitting the actuating lever to operate the release lever and, in the locked position of the lock means, elastically deforming and permitting the actuating lever to move independently of the release lever and without displacing the release lever into the actuated position.
Thus with this system the elastic link between the actuating lever and the release lever allows the lock member having the abutment to move even when the actuating member is in the actuated position. If a person pulls on a door handle and holds it out while another person actuates the unlock function of the remote, the door will open. Similarly if the remote is actuated to lock the door while the door handle is pulled out, once the handle is released, the door will be locked. In other words the elastic link will store up the force and use it to operate the release lever once it is unblocked.
Furthermore according to the invention a pivot carries the actuating lever and the link is a torque spring carried on the pivot. This torque spring has one leg engageable with the release lever and the link is in a path of the actuating lever. The spring is stiff enough that, when the release lever is not blocked, it can transmit sufficient force to the release lever to trip it and operate the pawl.
The abutment of the lock member has according to the invention a surface directly engageable with the release lever in the locked position. The actuating lever and release lever can be coaxially pivoted or mounted on separate parallel but offset pivots.
The release lever in accordance with the invention has an arm against which the one leg of the torque spring bears. The torque spring has another arm anchored to a body of the release lever. More particularly the release lever is L-shaped and has one arm engageable with the one leg of the torque spring and another arm engageable with the pawl. The one arm of the release lever is engageable radially of a pivot axis of the locking lever with the abutment.
The system of this invention can also have an inside actuating lever pivoted on the lock housing and a coupling lever pivoted on the locking lever and displaceable between a position coupling the inside lever to the pawl and a position decoupling the inside lever from the pawl. Thus the invention is perfectly applicable to a standard door lock with an inside handle, an outside handle, and inside locking element such as a button, an outside locking element such as a key cylinder, and a powered remotely controlled lock system.